In order to solve the contradiction between high repetition rate of fundamental wave and high average power of second-harmonic wave, a new 1064 nm/532 nm dual-wavelength composite jamming laser with high-repetitive frequency was designed. The composite output characteristics of the laser were obtained by the static analysis of the pump source′s efficiency, heat and force distribution of crystal, and by the Gauss mode of laser. The influence on the dual wavelength composite output was analyzed by changing the Q-switching frequency, the length of the second harmonic generation crystal and by simulating the thermal effect of second harmonic generation crystal. It is found that the high frequency of fundamental wave should be satisfied first, and the output power of second harmonic wave can be improved by optimizing the length of the second harmonic generation crystal and by controlling the temperature of second harmonic generation crystal under the condition of the constant pumping power and the structure of the resonator. The simulation conclusion was verified by an experiment. The experimental results show that when the length of KTiOPO4 crystal is chosen as 12 mm, the transmissivity of the output mirror is fixed to 10%, and the Q-switching frequency is selected as 50 kHz, the average output power of the fundamental wave is 18.98 W, and the average power of the output of second harmonic wave is 2.22 W. 